Device for locking turbomachinery blades

ABSTRACT

A blade-locking device, for locking radially projecting blades on a rotor, includes a spacer having a passage therethrough. The passage is accessible by means of an axial separation occurring at one side of the spacer; and the spacer is resiliently deformable to permit spreading of the separation from its undeformed position and returning the separation to its undeformed shape. A locking pin, having enlarged oblong integral ends at opposite extremities thereof, is formed and dimensioned so as to reside within the passage in a friction fit with each of the aforementioned ends projecting beyond the respective spacer extremity. The pin is disposed within the passage by deforming the spacer to enlarge the separation beyond the width necessary to receive the thickness of the pin and placing the pin therein. The pin is rotatable within the passage to a first position wherein one of the ends may pass freely with the spacer through a gap left between a blade tang and rotor slot to be interlocked. In a second position, the ends serve to engage and retain, respectively, the rotor and the blade tang.

United States Patent [191 Manharth in] 3,832,092 1451 Aug. 27, 1974DEVICE FOR LOCKING TURBOMACHINERY BLADES Gary B. Manharth, Milford, Ohio[73] Assignee: General Electric Company,

Cincinnati, Ohio [22] Filed: Oct. 19, 1973 [21] Appl. No.: 407,946

[75] Inventor:

Primary Examiner-Everette A. Powell, Jr.

Attorney, Agent, or FirmDerek P. Lawrence; Lee H.

Sachs ABSTRACT A blade-locking device, for locking radially projectingblades on a rotor, includes a spacer having a passage therethrough. Thepassage is accessible by means of an axial separation occurring at oneside of the spacer; and the spacer is resiliently deformable to permitspreading of the separation from its undeformed position and returningthe separation to its undeformed shape. A locking pin, having enlargedoblong integral ends at opposite extremities thereof, is formed anddimensioned so as to reside within the passage in a fric tion fit witheach of the aforementioned ends projecting beyond the respective spacerextremity. The pin is disposed within the passage by deforming thespacer to enlarge the separation beyond the width necessary to receivethe thickness of the pin and placing the pin therein. The pin isrotatable within the passage to a first position wherein one of the endsmay pass freely with the spacer through a gap left between a blade tangand rotor slot to be interlocked. In a second position, the ends serveto engage and retain, respectively, the rotor and the blade tang.

l3 Claim, 8 Drawing Figures DEVICE FOR LOCKING TURBOMACHINERY BLADESBACKGROUND OF THE INVENTION The present invention relates toturbomachinery rotors and more particularly to means for locking rotorblades within rotor slots.

In the manufacture of bladed turbomachinery rotors, it is commonpractice to mount the blades on the rotor through the use of dovetailtangs formed at the base of the blades which tangs are received bycorresponding slots formed across the periphery of the rotor. It hasbeen a commonly accepted practice, also, and particularly in gas turbineengines for the propulsion of aircraft, to lock the blades within therotor slots by the use of bent metal strips. These are slipped throughthe rotor slot and their ends are bent so that they overlie both thetang and adjacent portions of the side of the rotor. This is a simplearrangement which enables individual blades to be replaced, if desired.It has the disadvantage, however, that relative movement between theblade and the rotor in the axial direction will be absorbed bydeformation of a portion of the retainer. While such a retainer can bedesigned to function satisfactorily if an attempt is made to reuse it,reliability problems can arise.

As a related problem, certain blades having large radial dimensions havebeen improved by means of the addition of shroud structures either atmidspan or in the tip area. In order to properly position a plurality ofsuch blades so that the shroud segments associated with the individualblades successfully interlock to form a shroud, means must be providedfor defining the radial position of the blade tangs. The bent metal tabretainers of the prior art are not particularly well suited for such ause. Shrouded rotors require that the blade be shifted radially inwardlybefore it can be individually removed from the slot. Such action isinhibited by these retainers.

Another major drawback of the conventional and prior art blade lockingdevices, whether of the bent metal tab type or other types, is that theygenerally require access from both sides of the blade slot for insertionand removal. In some cases, engine design requirements'make itimpractical or inconvenient to provide such access during routinemaintenance or the like where it is desired to remove one or moreblades.

Certain advances in the art in this area have led to the introduction ofblade-locking devices which do provide a positive lock for the bladeswithout relying on bendin g of any of the component parts of the lockingdevice, and which do permit blade insertion and removal where access isavailable only to one side of the rotor. Unfortunately, such lockingdevices have had the disadvantage that they are comprised of multipleseparate components which must be separately manipulated during eachremoval and insertion. The result is that the insertion and removalprocess is relatively cumbersome and involves potential faulty partsassembly or placement.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide a simplified blade-locking device of the generalcharacter described which reliably retains blades in a predeterminedaxial position with respect to a rotor and which permits easydisassembly and assembly with few separate parts and minimummanipulation.

In order to accomplish this, as well as further objectives which willbecome apparent hereinafter, the present invention provides ablade-locking device for locking radially projecting blades on a rotor,each blade having a dovetail tang at its radially inward end and'therotor having dovetail slots extending across its periphery from oneaxial side of the rotor to the other, each blade being received in oneof the slots with a radial space between the tang and the bottom of theslot. The locking device includes a spacer having a' heightapproximating the radial dimension of the radial space, a locking pinhaving a length greater than the length of the spacer and also havingfirst and second enlarged ends which project beyond the spacer. The twoends of the pin have generally oblong configurations and are oriented toproject in opposite directions from the centerline of the pin. One ofthe ends has a width no greater than the radial dimension of theaforementioned radial space and a height greater than that radialdimension, so that it will pass through the radial space in oneorientation but not in a second orientation. The spacer has a passagefor receiving the pin and permitting it to rotate so that the pin can bepositioned with its ends arranged to pass, with the spacer, through theradial space. Alternatively, the pin can be rotated into a positionwherein the ends lock the tang in the slot by means of engaging both theblade tang and rotor assembly.

DESCRIPTION OF THE DRAWINGS The present invention will become moreclearly understood by reference to the following description taken inconjunction with the appended drawings wherein:

FIG. I is a radial cross section view of a fan blade and rotorcombination to which the present invention has been applied;

FIG. 2 is an axial view of a rotor stage incorporating blade and lockingmeans according to the present invention;

FIG. 3 is a view along line 3-3 of FIG. 2 disclosing the integral shroudstructure of the blades;

FIG. 4 is an exploded view of the spacer and locking pin structure ofthe present invention;

FIG. 5 depicts the spacer and locking pin in cooperation and in onerelative orientation thereof;

FIG. 6 is a section view through the spacer and locking pin combinationalong line 66 of FIG. 5;

FIG. 7 is an enlarged section view of the area of cooperation betweenthe locking device of the present invention and the blade and rotorcombination; and

FIG. 8 is a section view along line 8-8 of FIG. 7.

DETAILED DESCRIPTION Referring now to the drawings, the presentinvention is depicted in one fonn thereof individually as well asapplied to its normal environment. In FIG. 1, a rotor blade 10 having alarge radial dimension is depicted in combination with a rotor disc 12.The blade is typical of blades of this fashion in its incorporation ofan airfoil 14, a platform 16, and radially extending tang 18. Inaddition, this blade incorporates a segmented midspan shroud 20 which isadapted to cooperate with similar shroud segments of adjacent blades tosupport the blades against undesired movement. (Such shrouds areutilized to strengthen blades whose radial length and structural shapemake them relatively flimsy).

Referring now to FIGS. 1 and 2, the rotor 12 includes a plurality ofdovetail slots 22 which are adapted to receive the tangs 18 of theblades in a retaining relationship. The rotor slots 22 are spacedcircumferentially about the rotor and extend across its periphery fromone axial side thereof to the other. In addition, the slots 22 are ofsuch depth that, upon receiving the tang 18 of each blade 10, there isdefined between each tang and the bottom of each slot a space 24 havingapredetermined radial dimension 26. This space serves the function ofpermitting individual blades to be dropped radially inwardly withrespect to the rotor prior to removal in order to disengage the shroudsegments from contact with one another. (FIG. 3 depicts a top view ofadjoining blades disclosing the cooperation of mating segments 20 of themidspan shroud. In order to withdraw a blade axially from cooperationwith the rotor, it is first necessary to remove the associated segment20 from its interlocking relationship with similar segments). The rotor12 further includes a conical support 28 by which it is linked to ashaft to provide rotation thereto. In addition, the rotor includes aflange 30 to which is bolted a hollow nose cone structure 32 by means ofanother flange 34 carried by the nose cone.

Rotors of the variety thus described generally rotate with extremelyhigh velocities. As a result, in absence of effective means formaintaining axial blade position, the reaction of the airfoils toforeign object impingement, blade tip rub, or the'air passingtherethrough would tend to drive the blades out of the slots 22. If suchwere to occur, extensive damage could be done to the associated engineand its surroundings. As a result, it has become necessary to deviseeffective and reliable means for maintaining the blades in theirrelationship with the rotor. The present invention accomplishes this bymeans of utilizing the space 24 and placing therein a spacer and lockingpin combination to positively interconnect the blade tang 18 with therotor 12 in a releasable fashion and further to permit easy withdrawalthereof even though access might be limited to a single side of therotor. Furthermore, the present invention offers a uniquely simplifiedcombination for accomplishing these ends.

Referring to FIGS. 4 and 5, a locking device, according to the presentinvention, is depicted in its disassembled and assembled states. Inaddition, the locking pin is shown rotated in first and secondsignificant orientations with respectto the spacer. Generally, thelocking device comprises a spacer 40 and a locking pin 42. The spacer 40is. dimensioned so as to have a height or thickness approximating theradial dimension 26 of the radial space 24. In addition, the spacer hasa horizontal dimension or width approximating the width of the space 24.In the present embodiment, the spacer is generally U-shaped in crosssection with a passage 44 extending for its entire length in the axialdirection. The passage is open-ended at the ends 46 and 48 of the spacerand is further accessible by means of an axial separation 50 in thespacer which extends substantially the entire length of the passage.

In the present. embodiment, the spacer includes first and second lateralsegments 52 and 54, each segment formed to a predetermined length. Thesegments may be formed of a resilient plastic material or of some othereasily fabricated material. In addition, the spacer includes aresiliently deformable spring member 56 which receives and retains thelateral segments in opposed space relationship. The segments aremaintained a predetermined distance from one another forming a gap, thegap defining the aforementioned passage 44. In addition, the gappartially defines the separation 50.

The spring member 56 is generally U-shaped and retains the lateralsegments 52 and 54 one to each side of the U." The open end of thespring member further defines the separation 50. In the presentembodiment, each of the lateral segments 52 and 54 includes a lobe orenlarged section near each of its ends and a reduced section near itscenter. The spring member 56 surrounds and is secured to the reducedportion of the segments. It is to be noted that in this configuration,the flexibility of the spring member 56 permits a spreading of theseparation 50 in order to increase the accessibility of the passage 44.

The locking pin 42 has a length greater than the length of the spacerand further has first and second integral enlarged ends 60 and 62. Eachof these ends has a generally oblong configuration and each ispositioned in an eccentric fashion with respect to the pins so that amajority of its bulk protrudes'to a single side of the pin. The end 62is dimensioned so that its width 64 is no greater than the radialdimension 26 of the radial space 24. Hence, in one orientation of thepin, the end 62 is of such size that it will pass through the space 24.The end 62 furthermore has a height 66 (which is measured in a directiongenerally perpendicular to the width 64), which is greater than theradial dimension of space 24. As a result, with the pin oriented in asecond position, the end 66 will not pass through the space 24.

The other oblong enlarged end 60 of the pin 42 likewise has a height 68which is greater than the radial dimension of the space 24. This height68 is directed in a sense or direction opposite that of height 66 of theend 62. In other words, the height of end 60 is generally parallel tothe height of end 62 but extends in the generally opposite directionwith respect to the centerline of the pin. In its assembled position,the locking-device of the present invention is depicted in FIG. 5wherein the locking pin 42 and spacer 40 are assembled with the pinretained within passage 44 to which it is accessible by means ofseparation 50. When retained in the passage 44, the pin 42 is rotatabletherein to change the angle of orientation of the first and second endswith respect to the spacer. To inhibit undesirable angular rotation, thespacer and pin may engage one another frictionally in order to retardthe rotation of the pin within the passage- To facilitate thepositioning of the pin within the passage of the spacer, the spacerincludes the resiliently deformable spring 56 which permits spreading ofthe separation 50 for easy entry of the pin while also enabling thespacer to return elastically to its undeformed position. Additionally,the frictional engagement be tween the pin and spacer are enhanced bymeans of this spring. In order to achieve a reliable retention of thepin within the spacer, the separation 50, in its undeformed position,has a width smaller than the thickness of at least a portion of the pin42. In the present configuration, the pin is generally cylindrical inthe cross section and the passage is generally circular.

When the pin is positioned within the spacer and its ends 62 and 60extend beyond the spacer, it is desirable to prevent relative axialmotion between the pin and the spacer. In order to accomplish this, thepresent embodiment includes radius changes in the pin which result inthe formation of shoulders 70 and 72. These shoulders mate with abuttingshoulders 74 and 76 defined within the passage 44 by similar radiuschanges and combine to form securing means for preventing undesiredaxial relative motion.

Referring to FIGS. 7 and 8, assembly of the rotor and blade combinationwill be described, assuming that the rotor has already been positionedin the engine framework and that a number of blades have already beenpositioned thereon. Each additional blade is applied as follows.

An individual blade 10 is brought into proximity with the rotor 12 andis attached thereto by sliding the dovetail tang 18 into a mating slot22. The new blade is then lifted radially outwardly until its dovetailtang is brought up tight against mating portions of the associated slot.At the same time, the shroud segment 20 of the new blade is interlockedwith the shroud segments of adjacent blades. In order to maintain theblade in its radial and axial positions, the blade-locking device of thepresent invention is applied.

First, the locking pin 42 is snapped into frictional engagement withinthe passage 44 of the spacer 40 by way of expandingthe separation 50 tothe point where the pin will fit therethrough and into the passage.Then, the spring 56, which has been tensed to accomplish this spreading,is released and recloses the separation 50 engaging the pin. It is to benoted that this is a simple manipulation which can be quickly and easilyaccomplished and could be performed with one hand by the assembler.

Having thus been assembled, the locking pin is rotated into the positionshown in FIG. 5 wherein the width 64 of end 62 is aligned with thethickness of the spacer so as to pass freely through the space 24 asindicated above. This action is accomplished by the assembler by meansof sliding the spacer and pin combination through the space to thedesired axial position thereof. At this point, the blade 10 is held inthe desired radial position by means of the presence of the spacer 40.In order to accomplish axial retention of the blade, the pin 42 isrotated from its present position (that is, with the height of the end62 generally perpendicular to the radial dimension 26 of the space 24)to a second position wherein the height 66 of the end 62 is generallyparallel to the radial dimension of the space 24. In this secondposition, the position illustrated in FIGS. 7 and 8, the end 62 engagesand hooks upon an abutting portion 80 of the rotor 12. (While the end 62is depicted as being generally hook-shaped, any generally oblongconfiguration will suffice where a first dimension thereof is such thatthe end may pass through the space 24 while a second dimension thereofis such that the end will be prevented from passing therethrough).

The pin 42 having thus been rotated into this second position, whereinend 62 is in registry with the rotor 12, the pin cannot be removedaxially in the direction in which it was applied. Furthermore, the end60 has its height 68 so arranged that, as described above, it extends ina direction generally opposite that of the end 62. Due to thischaracteristic, the rotation of the pin 42 into the position lastdescribed will result in bringing end 60 into registry with a portion ofthe blade tang 18. This is also shown in FIG. 7. At this point, theblade has been assembled to the rotor and is now retained effectively inboth the radial and axial positions.

Subsequently, the nose cone 32 is brought into position and boltedthrough flange 34 thereof to flange 30 of the rotor 12. It is noted inFIG. 8 that the bolts 82 are spaced circumferentially about the rotor,and that a plurality of apertures 84 also spaced around the flange 34permit the protrusion of a portion of end 60 therethrough. Due to thefact that the protruding portion lies eccentrically to a single side ofthe centerline of the pin 42, and due to the selected dimensions of theaperture 84, undesired rotation of the pin 42 within the spacer isfurther hampered.

In order to ensure proper orientation of the spacer with respect to thespace 24 upon assembly, to maintain the angle of orientation of thespacer with respect to the space during engine operation, and to sealthe space 24 against the undesired leakage of air therethrough, thepresent invention further provides rib means for sealing as well asdefining and maintaining the angle of orientation of the spacer when thespacer is disposed within the space. This means includes, in the presentembodiment, a pair of upstanding ribs 88 and 90 which are positionednear one end of the spacer 40, and more particularly the end which is toremain on the side of the rotor accessible by the assembler. As can beseen in FIG. 2, the shape of the blade tang 18 combines with the shapeof the slot 22 to define a pair of detents 90 and 92 which have roughlythe same outline in the cross section as do the ribs 88 and 90. Thedetents serve to accept the ribs and retain them in a sealingrelationship in a predetermined position. Furthermore, the detentsextend only a limited distance into the axial direction with respect tothe rotor and therefore prevent the reversed insertion of the pin andspacer combination. The sealing capability of the ribs is important inorder to eliminate efficiency losses associated with leakage of airthrough space 24.

Thus, as has been described in one embodiment, the present inventionprovides a strong and effective bladelocking device for retaining rotorblades in a predetermined radial and axial position with respect to anassociated rotor. It can be appreciated that, due to the extremelysimplified two-piece spacer and pin combination, assembly is radicallyenhanced when compared to prior art devices requiring the cumbersomebending of metal pieces or assembly of multiple component lockingdevices. Furthermore, it can be appreciated that ease of assembly anddisassembly is greatly improved by pennitting the entire assemblyprocess to occur from access to a single axial side of the rotor.Additionally, the integral character of the ends 60 and 62 with pin 42make for a very strong and reliable retaining mechanism not dependentupon threaded connections or the like.

Having thus described the present invention in one embodiment, it isclear that numerous substantial variations thereof may be made withoutdeparting from the scope of the present invention. For example, thestructural interrelationships between the locking pin 42 and spacer 40are dictated more by the configuration of the space 24 between the baseof the tang 18 and slot 22 than by the inventive dictates of thisinvention. Any

variation which functions in substantially a similar fashion andprovides the improved characteristics of this invention would fallhereunder without necessarily even resembling the embodiment depicted.Other variations might change the shape of the enlarged ends 60 and 62which have been depicted as generally hookshaped but can be varied toany eccentric and oblong configuration. Similarly, while it is desirablethat the pin 42 be generally cylindrical in cross section, it may becomedesirable to make this cross section noncircular and the mating passage44 cross section noncircular for the purpose of increasing thedifficulty of rotation of the pin within the passage. Other variationshereof will occur to those skilled in the art. I

What is claimed as new and desired to be secured by letters Patent ofthe United States is:

1. A blade-locking device for locking radially projecting blades on arotor, each blade having a dovetail tang at its radially inward end andthe rotor having dovetail slots extending across its periphery from oneaxial side of the rotor to the other, each blade being received in aslot with a radial space between the tang and the bottom of the slot,said device comprising:

a spacer having a height approximating the radial dimension of saidradial space;

a locking pin having a length greater than the length of the spacer andalso having first and second enlarged integral ends, said first andsecond ends having generally oblong configurations, said first endhaving a width no greater than the radial dimension of said radial spaceand a height greater than said radial dimension, and said second endhaving a height greater than said radial dimension; and

said spacer having a passage along its length for receiving said pin,said passage being accessible to said pin by means of a separation insaid spacer extending substantially the entire length of said passage,and said pin being rotatable within said passage to change the angularorientation therewith of said first and second ends.

2. The device of claim 1 wherein said spacer includes resilientlydeformable material facilitating spreading of said separation for easyentry of said pin, and permitting elastic return of said separation toits undeformed position.

3. The device of claim 2 wherein said separation, in its undeformedposition, has a width smaller than the thickness of a portion of saidpin.

4. The device of claim 3 wherein said spacer is generally U-shaped inthe cross section, and said pin is generally cylindrical.

5. The device of claim 1 wherein, when said pin is disposed within saidpassage and said spacer is disposed within said spacer, said pin isadapted to be rotated from a first position wherein said height of saidfirst end is generally perpendicular to said radial dimension of saidspace, to a second position wherein said height of said first end isgenerally parallel to said radial dimension of said space.

6. The device of claim 5 wherein said first end engages said rotor insaid second position.

7. The device of claim 6 wherein said second end has its heightgenerally parallel to the height of said first end, but extending in thegenerally opposite direction so that, when said pin is in said secondposition, said second end engages said tang.

8. The device of claim 1 wherein said first and second ends of said pinextend axially beyond said spacer when said pin is disposed within saidpassage; and said device further comprises securing means for preventingaxial relative movement between said pin and said passage.

9. The device of claim 8 wherein said pin and said passage mate in afriction fit to prevent undesired relative angular movement; and whereinsaid securing means comprises first and second abutting shouldersassociated respectively with said pin and said passage.

10. The device of claim 1 wherein said spacer includes positioning meansfor defining and maintaining angular orientation of said spacer whendisposed within said radial space, and seal means for preventingundesired leakage through said radial space.

11. The device of claim 10 wherein said positioning and seal meansincludes an upstanding rib carried by said spacer, said rib adapted toengage a detent formed between said tang and said slot.

12. The device of claim 1 wherein said spacer comprises:

first and second lateral segments, each segment formed to apredetermined length; and

a resiliently deformable spring member for receiving and retaining saidlateral segments in opposed, spaced relationship separated from oneanother by a predetermined gap. said gap defining said passage andpartially defining said separation.

13. The device of claim 12 wherein said spring member is generallyU-shaped and retains said lateral segments one to each side of the U,and wherein the open end of said spring member further defines saidseparation.

1. A blade-locking device for locking radially projecting blades on arotor, each blade having a dovetail tang at its radially inward end andthe rotor having dovetail slots extending across its periphery from oneaxial side of the rotor to the other, each blade being received in aslot with a radial space between the tang and the bottom of the slot,said device comprising: a spacer having a height approximating theradial dimension of said radial space; a locking pin having a lengthgreater than the length of the spacer and also having first and secondenlarged integral ends, said first and second ends having generallyoblong configurations, said first end having a width no greater than theradial dimension of said radial space and a height greater than saidradial dimension, and said second end having a height greater than saidradial dimension; and saiD spacer having a passage along its length forreceiving said pin, said passage being accessible to said pin by meansof a separation in said spacer extending substantially the entire lengthof said passage, and said pin being rotatable within said passage tochange the angular orientation therewith of said first and second ends.2. The device of claim 1 wherein said spacer includes resilientlydeformable material facilitating spreading of said separation for easyentry of said pin, and permitting elastic return of said separation toits undeformed position.
 3. The device of claim 2 wherein saidseparation, in its undeformed position, has a width smaller than thethickness of a portion of said pin.
 4. The device of claim 3 whereinsaid spacer is generally U-shaped in the cross section, and said pin isgenerally cylindrical.
 5. The device of claim 1 wherein, when said pinis disposed within said passage and said spacer is disposed within saidspacer, said pin is adapted to be rotated from a first position whereinsaid height of said first end is generally perpendicular to said radialdimension of said space, to a second position wherein said height ofsaid first end is generally parallel to said radial dimension of saidspace.
 6. The device of claim 5 wherein said first end engages saidrotor in said second position.
 7. The device of claim 6 wherein saidsecond end has its height generally parallel to the height of said firstend, but extending in the generally opposite direction so that, whensaid pin is in said second position, said second end engages said tang.8. The device of claim 1 wherein said first and second ends of said pinextend axially beyond said spacer when said pin is disposed within saidpassage; and said device further comprises securing means for preventingaxial relative movement between said pin and said passage.
 9. The deviceof claim 8 wherein said pin and said passage mate in a friction fit toprevent undesired relative angular movement; and wherein said securingmeans comprises first and second abutting shoulders associatedrespectively with said pin and said passage.
 10. The device of claim 1wherein said spacer includes positioning means for defining andmaintaining angular orientation of said spacer when disposed within saidradial space, and seal means for preventing undesired leakage throughsaid radial space.
 11. The device of claim 10 wherein said positioningand seal means includes an upstanding rib carried by said spacer, saidrib adapted to engage a detent formed between said tang and said slot.12. The device of claim 1 wherein said spacer comprises: first andsecond lateral segments, each segment formed to a predetermined length;and a resiliently deformable spring member for receiving and retainingsaid lateral segments in opposed, spaced relationship separated from oneanother by a predetermined gap, said gap defining said passage andpartially defining said separation.
 13. The device of claim 12 whereinsaid spring member is generally U-shaped and retains said lateralsegments one to each side of the ''''U,'''' and wherein the open end ofsaid spring member further defines said separation.